STRUCTURE AND FUNCTIONS OF THE EAR OF THE 



SQUETEAGUE. 



By G. H. PARKER, Ph. D., 

 Professor oj Zoology, Harvard University. 



INTRODUCTION. 



Although fishes have no external ears, they have long been known to pos- 

 sess internal ears which in complexity of structure often approach even those of 

 the higher vertebrates. It is therefore natural to expect that the functions 

 ascribed to the internal ears of birds, mammals, etc., would be found in one 

 form or another among the fishes. These functions are chiefly three — first, 

 hearing, which is historically the earliest function to be ascribed to the internal 

 ear; second, an influence on bodily equilibrium both when the body is at rest 

 and when it is in motion, a view founded upon the experimental investigations 

 of Flourens (1828); and, third, an influence on tonus or strength of contraction 

 of the skeletal muscles, as demonstrated first by Ewald (1892). 



The ear of the squeteague {Cynoscion regalis) is a well-developed organ 

 and shows in a striking way all the essential parts of the ears in fishes. The 

 male squeteague, moreover, is well known to produce sounds through a special 

 mechanism not possessed by the female (Tower, 1908). Because of these 

 structural conditions and of the highly specialized habit of sound production 

 in these fishes, I was led to make an investigation of their ears. The only 

 objection to this species for such study is its lack of vitality. It can not be 

 kept many days in confinement, even in large fish boxes in the open sea, and 

 it is not resistant to the effects of operations. Nevertheless, the exceptionally 

 favorable conditions at the Woods Hole Laboratory of the Bureau of Fisheries 

 made it possible to overcome these obstacles sufficiently to carry out the pro- 

 posed work. 



ANATOMY OF THE EAR. 



The internal ears of the squeteague are relatively large organs and are 

 lodged in the lateral walls of the posterior part of the skull. In a dry preparation 

 of the skull their position is indicated on the ventral side by two smooth elon- 

 gated bony capsules (fig. 4, pi. cxxii) , whose posterior ends lie close together near 



1213 



